Right. I believe the air hat is a de-tuning device to reduce noise (read
resonance).
I don't think any statically shaped intake on an RPM varying machine is going
to be all one way to the other 'good' or 'bad'. Also I think there are
non-resonant based positives to a longer intake that are not frequency based at
all; simply that fact that a longer/larger moving column of air provides more
inertia to there is overall more pressure at the intake valves.
Bose concept is not anywhere near the same as Helmholz concept. Bose concept
is based more on odd harmonics I believe and 1/2, 1/4, 1/8... wave lower
harmonics of those odd harmonics or something like that. Helmholz is a single
frequency resonant device. The Bose concept somehow gets a smaller tube to
resonate over a wide range of frequencies lower than normal, not just a single
lower frequency. But I am far from an expert and, like you, are more wondering
than knowing.
Thanks for the input.
Bruce Bridges wrote:
> Marty,
> Bose Chamber or Helmholz resonator cavity? I havnt seen the 4.7 air hat
> (yet) but manytimes the designer needs to reduce a natural resonance set up
> by the length of the pipe and the "driving frequency" in this case , the
> pulasations from the 8 pistons. A bad resonance can retard flow and cause
> control problems... Or make nice music, like a flute (or a
> banshee)...depends on the frequency of the standing wave and the magnitude
> of the driving force! It pays to do some quick "thumbnail" analysis before
> sinking the family farm into a pneumatic design...
> I should be getting my first 4.7 TB this week to get a good look at its
> "issues" if any! ...
> Bruce
> ----- Original Message -----
> From: Marty Galyean <mgalyean@acm.org>
> To: <dakota-truck@buffnet.net>
> Sent: Monday, October 16, 2000 6:29 PM
> Subject: Re: DML: RE: ABS looooong po'boy intake installed on 4.7 - wow!
>
> > Yeah, you could put it that way. But from my point of view I just arrived
> at
> > the longet section of ABS tubing I could get under the hood and it happens
> to
> > be 'S' shaped. I think mine might be longer than the 'Z', and more
> turbulent
> > inside due to more bends and the ABS joins. But yes, I get the same
> signature
> > effects. I used the 9" cone. Why? well I figured it couldn't hurt. And
> if I
> > do some TB upgrade later it may end up being more appropriate anyway.
> BTW,
> > I was the one who first suggested the air hat was Bose-chambered and I now
> am
> > sure I was incorrect. There are chambers, but I don't think they are of
> the
> > Bose variety. I now believe they are de-tuned to reduce noise
> (resonance).
> > Kind of like anit-bose chambers or something. I vaguely recall that a
> Bose
> > chamber comes off a tube at a critical point 1/3 down the tubes length and
> that
> > the length of the chamber itself is involved in the equation. The end
> result
> > is a small package with deep resonance. Like Danny Devito.
> >
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